1. Field of the Invention
The present invention relates generally to Ethernet networks and, more particularly, to a system and method for enhanced accuracy in cable diagnostics of cable length.
2. Introduction
Cable diagnostic play a key role in the management of various networks. Various forms of cable diagnostics can be used to detect and identify cable faults, cable length, cable topologies, etc. An identification of cable length is particularly useful in determining the potential performance of a link over that cable, which enables diagnostics and/or enables other applications.
To illustrate such an impact, consider an example application such as power over Ethernet (PoE). In a PoE application such as that described in the IEEE 802.3af and 802.3at specifications, a power sourcing equipment (PSE) delivers power to a powered device (PD) over Ethernet cabling. Various types of PDs exist, including voice over IP (VoIP) phones, wireless LAN access points, Bluetooth access points, network cameras, computing devices, etc. In an enterprise network, various PDs can be deployed on a permanent or non-permanent basis at various locations (e.g., conference rooms) situated throughout the enterprise facility.
In powering these various PDs, a key piece of information is the length of the cable between the PSE and the PD. In one example, this length information can be used to calculate or otherwise determine a resistance of the cable link. The resistance of the cable link in turn can be used to identify a voltage drop and/or power loss that can be attributed to the cable link. For a given PD deployment, the voltage drop and/or power loss can play a key role in the determination and allocation of an accurate power budget attributable to that port. As the resistance of the cable is proportional to the length of the cable, an accurate determination of the cable length is critical to any calculations or assessments that are based on the resistance of the cable link.
As would be appreciated, the determined length of the cable can be useful in various diagnostic capacities either alone or in combination with the particular needs of a given application. There are many applications beyond PoE that can use the cable length information. What is needed therefore is a mechanism that enables enhanced accuracy in the cable diagnostics of cable length.